1. Field of the Invention
An object of the invention is a linking device between a termination of a cable and a contact element. It can be used more particularly in the field of interconnections in aeronautics. The cable comprises metal strands held together in a cable sheath. These strands have to be connected to the connecting element so that it can provide continuity of the electrical signal at the junction between the cable and a corresponding device. However, the materials of which they are made have different natures and different physical properties. Now, such elements and cables undergo major physical stresses in terms of pressure and temperature variations owing to their use in onboard machinery. Consequently, it can happen that it becomes impossible to guarantee a permanent connection. The invention proposes an approach implementing an intermediate element used to compensate for the effects of temperature variations in particular.
2. Description of the Prior Art
In the prior art, there is a known contact element designed to receive a termination of a cable in a receiver of this contact element. The receiver generally forms a cylindrical barrel or sleeve into which a bared portion of the cable may be inserted. The sleeve is generally designed with a flared portion at an outlet point of this sleeve so that it can also receive a non-bared portion of the cable. The cable is held within the sleeve because this sleeve is then crimped around the bared portion, and around the non-bared portion of the cable.
This contact element generally has a contact end opposite the end giving access to the aperture that opens into the sleeve. This contact end generally has an elongated shape and has either a female termination or a male termination. The contact element is made in one piece: for example it is obtained by machining or turning. It is made out of copper and forms a solid piece.
In aeronautical applications and for reasons of weight, cables with copper strands cannot be used. This is why it is the use of cables with aluminum strands that is envisaged. Such strands have good characteristics of connectivity and contact resistance, and they weigh less than the copper strands.
To improve the contact made between the strands of the cable and the inner walls of the sleeve into which they are inserted, these inner walls are gold-plated beforehand. The problem posed by this gold-plating step is that, to be able to control the homogeneity of the gold-plating deposited on the inner walls of the sleeve when it has a diameter of about the millimeter, it is necessary to provide for a via hole that crosses the thickness of the contact and reaches the deepest level of the sleeve. The presence of this inspection hole raises a problem. Even if it ensures the quality of the deposited gold-plate layer, this hole subsequently has to be plugged so as not to impair the impervious sealing of the connection. The plugging of the inspection hole entails an additional step and is therefore a constraint. This plugging is obligatory to prevent the end of the cable inside the sleeve from being damaged by corrosion.
Finally, to make contact, as is the case in the prior art, the sleeve is crimped at a first level on the bared strands of the cable and at a second level on the sheath of the cable. The first crimping provides for electrical connection and, at the same time, mechanical strength. The second crimping provides for the impervious sealing of the connection at the sleeve aperture.
Owing to the conditions in which the connections are placed, i.e. the substantial and rapid temperature variations to which they are subjected, the differences in expansion coefficients between the aluminum and the copper cause a relaxation of the contact pressure and, at the same time, an increase in contact resistance that is detrimental to the quality of the connection.